It may be desirable to stop an engine at a same location each time the engine is stopped. An engine may be stopped before each engine start at nearly the same position if the engine may be rotated via a motor or other device. Alternatively, engine components including but not limited to engine valves, throttle, and spark timing may be adjusted during an engine stop to improve the possibility of the engine stopping at a same desired location. However, it may be difficult or cost prohibitive to adjust engine actuators or an electric machine such that engine stopping position is a same position for each engine stop. Consequently, engine emissions and/or engine run-up time (e.g., time from engine cranking until the engine reaches a desired speed, such as idle speed) may degrade or change depending on the engine stopping location.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for starting an engine, comprising: selecting a cylinder and providing two fuel injections during a compression stroke of the cylinder for a first combustion event since engine stop in response to a piston of the cylinder being within a third threshold number of crankshaft degrees before the cylinder's TDC compression stroke; and adjusting a ratio of fuel between the two fuel injections in response to intake valve closing timing.
By selecting a cylinder of an engine for a first fuel injection event since engine stop in response to the cylinder's position relative to the cylinder's top-dead-center compression stroke position, it may be possible to provide the technical result of reduced engine emissions and a short engine starting time. Further, a ratio of fuel between first and second fuel injections to the selected cylinder may be adjusted to improve combustion stability and engine starting robustness.
The present description may provide several advantages. In particular, the approach may improve engine starting consistency by reducing the possibility of engine misfire. Further, the approach may improve engine starting emissions by improving mixture ignitability. Further still, the approach may improve a driver's perception of engine starting.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.